This invention relates in general to an ultrasonically welded imaging member seam having an overcoat layer comprised of a polyester resin. Advantages associated with the imaging member of the present invention, in embodiments, thereof include for example, decreasing the delamination of the imaging member seam, resulting in an increase in the useful life of the seam especially on long term cycling of the member. Processes of imaging, especially xerographic imaging and printing, including digital, are also encompassed by the present invention. More specifically, the layered photoconductive imaging members of the present invention can be selected for a number of different known imaging and printing processes including, for example, electrophotographic imaging processes, especially xerographic imaging and printing processes wherein charged latent images are rendered visible with toner compositions of an appropriate charge polarity. Moreover, the imaging members of this invention are useful in color xerographic applications
In the art of electrophotography, an electrophotographic plate comprising a photoconductive insulating layer on a conductive layer is imaged by first uniformly electrostatically charging the surface of the photoconductive insulating layer. The plate is then exposed to a pattern of activating electromagnetic radiation such as light, which selectively dissipates the charge in the illuminated areas of the photoconductive insulating layer while leaving behind an electrostatic latent image in the non-illuminated areas. This electrostatic latent image may then be developed to form a visible image by depositing finely divided electroscopic toner particles, for example, from a developer composition, on the surface of the photoconductive insulating layer. The resulting visible toner image can be transferred to a suitable receiving member such as paper.
Electrophotographic imaging members are usually multilayered photoreceptors that comprise a substrate support, an electrically conductive layer, an optional charge blocking layer, an optional adhesive layer, a charge generating layer, a charge transport layer, and a protective or overcoating layer(s). The imaging members can take several forms, including flexible belts, rigid drums, and the like. The flexible belt may be seamless or seamed. These belts are usually formed by cutting a rectangular sheet from a web, overlapping opposite ends, and welding the overlapped ends together to form a welded seam.
For many multilayered flexible photoreceptor belts, an overcoat layer is usually employed on the backside of the substrate support, opposite to the side carrying the electrically active layers.
Various combinations of materials for charge generating layers and charge transport layers have been disclosed. U.S. Pat. No. 4,265,990 discloses a layered photoreceptor having a separate charge generating (photogenerating) layer and charge transport layer. The charge generating layer is capable of photogenerating holes and injecting the photogenerated holes into the charge transport layer. The photogenerating layer utilized in multilayered photoreceptors include, for example, inorganic photoconductive particles or organic photoconductive particles dispersed in a film forming polymeric binder. Inorganic or organic photoconductive materials may be formed as a continuous, homogeneous photogenerating layer. The disclosure of this patent is incorporated herein in its entirety by reference.
Examples of electrophotographic members having at least two electrically operative layers including a charge generating layer and a charge transport layer are disclosed in U.S. Pat. Nos. 4,265,990, 4,233,384, 4,306,008, 4,299,897 and 4,439,507. The disclosures of these patents are incorporated herein by reference in their entirety.
Delamination of the imaging member seam can cause problems in high speed automatic copiers; duplicators and printers which require extended cycling of the photoreceptor belt. For example, delamination has occurred in as few as 8,000 cycles. Overcoat layers will also occasionally delaminate due to poor adhesion to the supporting substrate. Delamination of belt seams has been found to be a primary reason for the failure mechanism of the belt before the end of the manufacturer""s proscribed lifecycle. An overcoat layer may be used to extend the life of the imaging member. It has been demonstrated that seam life can be improved by overcoating the imaging member belt seam with a protective coating.
The overcoat layer may be applied, for example, as a hot melt adhesive, spray coated, brush painted onto the seam, or the overcoat may be applied with a direct writing applicator device, for example, a xe2x80x9cmicro-penxe2x80x9d which is self-contained, completely integrated synchronous positive displacement pump or pumping system for producing precision deposited images of any fluid material or fluidizable material. Micro-pens are available commercially from Micropen Incorporated, a subsidiary of OhmCraft Incorporated, of Honeoye Falls, N.Y. Reference also for example, www.ohmcraft.com for additional description of the apparatus and other applications and capabilities. A further description of a direct writing applicator may be found in U.S. Pat. No. 4,485,387 to Drumheller, the disclosure of which is incorporated herein in its entirety by reference. Direct writing technology has been used in other areas to fabricate high precision printed circuit boards and other microelectronic devices comprising resistors, capacitors, interconnecting conductors, and the like devices. The feature sizes of such devices are very precise with respect to line width and line thickness. The direct writing apparatuses that are used to fabricate such devices are essentially high precision dispensing instruments that are capable of dispensing a wide range of liquids and pastes to form the above mentioned microelectronic devices.
What is still desired is an improved belt seam overcoat and application method that further extends the lifecycle of the belt, particularly for modified multilayered electrostatographic imaging members in a flexible belt configuration, and processes for fabricating these imaging members.
Disclosed herein is an electrophotographic imaging member comprising a supporting substrate, and
at least one imaging layer on one side of the supporting substrate,
a charge blocking layer,
an optional adhesive layer,
a charge-generating layer,
a charge transporting layer,
a seam overcoat layer opposite said at least one imaging layer comprising a coating solution of a polyester resin and having a thickness of from about 2 to about 4 micrometers, and a width of from about 2 to about 10 millimeters and wherein said polyester resin is present in an amount of from about 2 to about 40 percent by weight based on the total weight of said seam overcoat layer, and a binder.